/Engine/Source/Runtime/Engine/Public/GenericQuadTree.h
Given a 2D box, returns an array of elements within the box. There will not be any duplicates in the list.
template<typename ElementAllocatorType> void GetElements ( const FBox2D & Box, [TArray](API\Runtime\Core\Containers\TArray)< ElementType, ElementAllocatorType > & ElementsOut ) const